Lifting jack



M. B. LUCKER June 21, 1932.

LIFTING JACK Filed April 1, 1929 Patented June 21, 1932 JYUNITED sTATEs PA ENT: OFFICE MrLLann B. Luoimaor BENTON HARBOR, UCHIGAN, ASSIGNOR, BY MEsNE ASSIGN- MENTS, r THE DAYTON MALLEABLE IRON COMPANY, or DAYTON, OHIO, A con- P OR-ATIO N OF OHIO Application filed A ril 1,

My invention relates in general to lifting jacks and more particularly to a jack of the double screw type, that is to say, a jack comprising a standard in which aretelescoping- 1y mounted two telesco'pingscrew threaded members, which are adapted to bepr'ojected successively out of and into the'standard.

' The object of the present invention is to provide a simple means for causing the'suc-' 2c cessive pro ectlonfand retraction of the screw members relatively to the housing. I 7

Another object of my invention is to provide a simple and inexpensive brakingconnection between the standard and the'outer threaded member of the telescoping pair of screws, which is adapted yieldingly to hold the outer threaded member from rotation at certain: times whilepermitting its free rotation at other times, whereby to bring about 'the successiveprojection and retraction of erate in a simple manner with the standard whereby to carry out its function. i

' In short, the principal object of my present invention is to provide the above type of braking device which is most economical i302" tomanufacture and to assemble in the jack and which will provide very efllcientand rugged service and which, at "the same time, is capable of quick replacement.

These and other objects of my invention will be apparent from a perusal of the following specification when taken in connection with the accompanying drawing, wherein:

Figure 1 is a side view partly in section, illustrating the present day type of double screw lift jack and showing same provided with my improved braking device;

Figure 2 is a sectional view looking upwardly from the bottom of the jack;

Figure 8 is aperspective view of the bottom part of the outer screw of the ack;

Figure 4 is a perspective view of a coil spring which constitutes a part of the braking device.

To illustrate my invention, I have shown L FTING JA K 1929. Serial o. 351,511.

on the drawin its preferredembodiment and as adapted to a present day type of double screw lift ack. The jack comprises a standard2 of light metal provided with a base 4 upon which the jack" stands in an upright position, The upper portion of the jack is providedwith an integrally cast or otherwise formed yoke 6, housing the usual bevel gear 8, which in turn rests'upon the usual ball bearing '10 mounted on the upper portion of the standard 2, and within the yoke 6. The inner bore of the bevel gear 8 is formed with interior-threads 12, con-' stituting a rotatable nut. I

Means is provided for rotating the nut and this comprises a second bevel'gear 14 which is rotatably mounted in a laterally disposed bearing 16, integralwith the standard 2 and preferably at its top. This bevel gear 14 has an outwardly extending shank 18 which is hollow so as to receive. a turning crank, all as is well-known in the art.

Threading through the inner threads 12 of the nut 'WhlCh is formed integral with the bevel'gear-S, is a screw threaded, projectable member in the form of a sleeve 20. This sleeve has exterior threads 22 which engage thethreads 12 of the nut. In addition, there is a secondprojectable member 2 1 which telescopes within the sleeve 20. This second screw threaded projectable member is pro-' vided on its upper-end with the usual work supporting saddle 26 and'the exterior threads of this'second member 24 engage interior threads 28 formed on' the upper end of the outer screw sleeve 20. These-inner and outer screw i sleeves are provided with the usual stops for preventing their coming completely out of the standard-2 as is well known in the art, andalso in my prior-filed applications. In'additi'on toiconstituting stops, these screws 30, which are carried by the inner and'out'er j screws between the threads thereof, function to permit the successive projection and re traction of the threaded members.

The foregoing is all old in the art and is shown in my prior pending applications.

1 My present invention consists in asimple construction of means for preliminarily hold ing the outer screw 20 from rotation'during the rotary movement of the bevel gear 8, so as to cause the immediate projection of the sleeve and carrying with it the inner screw 24. In my present invention, I provide the standard 2 with a vertical guide-way 32, there beingon ly one such guide-wayand the same extending: from the. bottom of the jack upwardly to the ball bearing 10. Thebottom. of the outer screw or screw sleeve 20, is providedb'elow thelowermost part of the thread 22"with a cylindrical orunthreadedportion 34 which is smooth on its periphery. To cooperate with this surface, I provide a coil spring 36 having free ends 38 andlOwhich... extend laterally outwardly therefrom. order to place this coil spring. upon the cylindrical portion 34, the ends-38 and .40 of the spring are pulled sideways so as to increase the diameter of the coil spring, at which time it is then slipped over; the end 3% of the outer screw sleeve; The ends 38' and lOare then released so that they springtback. intofpositionsubstantially-as shown in Figure. 4, at. which time the convolutions of the coil spring. resiliently grip the smooth barrel-like pore tion 38; T-helower end of the screw sleeve 20 is then: pee-ned outwardly as at 42 so. as to hold. the spring-in placeand preventit from slipping off the endof the screw sleeve; The freeiends 38'and LOofthe coil spring arethen pressed together in the manner shown in Fi'g ure 2; of' the drawing, and. insertedthrough the bottom end of the guide-way 32 so that thesefree ends firmly but. slid'ablygrip the Walls-of. the guide-way 32. It will thus: be seen that in this position, thecoi-l spring'isf mounted to slidealongythe guide-way,- that is, vertically up anddown the standard-2, but is not permitted to: turn' angularly'with. respect tothe st andard2'. At.thesame:time,. the wirecoilswillgrip the: outer sleeve; 20." with sufficient force to prevent it from turning so that when thebevel gear "14 is rotated, it will rotate the bevel gear '8, whichin turn;

will cause the outer sleeve 20 t0. rise-.sincei-t;

is'heldfrom rotationv by ineanszoftmy imeproved friction brake. When. the stop contacts withthe underside ofthe beveligear 8,.this1will firmly wedgethenut a-nd'thezouterr sleeve together so that furtherrotati'onof the 3 nut, will cause the sleeve QOtorotate; Att'hi's'; time, the coil springsvof. the friction; brake:-

will slip upon the smooth barrelelike'porti'on:

has. come into contact, withthe. worli to be. lifted, then the outer screw willbegill' to be' projected upwardlyru-ntilt itltooxhas'reached-s its outermost limit, the samebeingirdefined by means offa similar-screwrmounted between.

the threads of the. inner" screw and" coming into: contact with the lowermost: interiorsthreadr'28 ongthe outer sleeve: I

assembly.

Having thus described my invention, what. I :cla'rm" as new and desireto secure by 'Let= ters-Patentis':

1. In a double screw 'liftjackfilie'combmation'with a standard provided with a guidewa a rotatable nut mounted on the upper en 'of said standardand provided with interior threads, means for. rotatingsaidnut, a tubular sleevehaving. exterior threads mounted within thethreaded nut, saidtubular. sleeve having at its upper end interior: threads, asecond threadedmember having? exterior threads engaging the interior: threads. of the tubular sleeve, and provided; with a work supporting head, the lowerend of said tubular sleeve havingaplain cyli-nd-ri.- calportion, acoiled;springresilientlygripping the exterior.threadsoffthe: interior'fpor tion with thefree ends of the-spring'engaging the walls .of-theguide-way, the lower end: ofsaid tubular sleeve being peenedv so. astor prevent the-inadvertent detachment of the; coiled spring,

2. A jack comprising a housingha-ving an: extending. groove and: having, rotatable; driving member, a threaded sleeve; project able by the driving member, meansacoinprise ingzazisingle strand of resilient:- wire" stock:

coiled into a plurality of. convolutions: with: the opposite endsrthereof projeetingsubstarratial ly radially, saidprojecting ends; being: normally substantially spaced: apart. when: unrestrained, said: coilr'embracing the sleeves at the IOWGI'iGIId, and withrthe projecting ends pressed together and; engaginginthesvertia cal groove of thenhousingr.

In' witness whereof, I havezherennto sub scribed my name:

MILLARDI B. LEG/KER 

